remove unused hljs styles from showcase
remove unused hljs styles from showcase

jdfreder/nteract,captainsafia/nteract,rgbkrk/nteract,jdetle/nteract,captainsafia/nteract,nteract/nteract,rgbkrk/nteract,captainsafia/nteract,jdetle/nteract,nteract/nteract,jdfreder/nteract,nteract/nteract,jdfreder/nteract,nteract/nteract,rgbkrk/nteract,nteract/composition,rgbkrk/nteract,jdetle/nteract,jdfreder/nteract,nteract/composition,rgbkrk/nteract,nteract/nteract,captainsafia/nteract,nteract/composition,jdetle/nteract